Method of making artificial leather



Patented May 15, 1934 METHOD OF MAKING ARTIFICIAL LEATHER Karl Haarburger, Reutlingen, Germany No Drawing. Application December 17, 1932,

Serial No. 647,831. 1931 1 Claim.

My invention relates to a method of making artificial leather from fibrous material.

It is an object of my invention to provide an" improved method for the purpose specified.

To this end, I impregnate a body of fibrous material with a binder between two foraminous holders. When the body has been impregnated with the binder, I squeeze it while still between performed heretofore, may be classified in two groups, as follows: I

According to the methods of thefirst group, the fibrous material is impregnated with a suitable adhesive as the binder by first preparing a pasty suspension or pulp of the fibrous material, then admixing the binder to the pulp, precipitating the binder on the fibres, dehydrating the pulp on a screen, and finally drying it. If required,'the dried product is pressed under any suitable pressure.

These methods have the drawbacks that in the preparation of the pulp, and particularly during the admixing of the binder, clots frequently form so that it is difficult or even impossible to obtain a uniform product; that it is difficult to work the binder into the material; and that loss of binder is inevitable during the dehydration.

According to the methods of the second group, the fibrous material, for instance shredded leather or cotton batten, is spread on' a suitable support, the binder is applied to the upper side of the material and worked into the material. Leather shreds are worked by rolling while cotton batten after having been coated with the adhesive or binder on one side, is covered with a second layer and the finished product is split if required.

These methods have the drawbacks that impregnation is difiicult, that they are complicated and require complicated equipment.

According to my invention, the drawbacks of the old methods are eliminated. In particular, the fibrous material is impregnated very thoroughly, there is no loss of binder or adhesive, and the equipment required is, comparatively speaking, very simple.

The product is almost equal to natural leather in strength, and it is by no means difiicult to impart to it the flexibility of leather by suitable softening agents.

Any fibrous material may be used for my method. A particularly. suitable material is cotton batten, but fabrics, dehydrated pulpsetc. may as well be used provided the structure of the material at all lends itself to the making of artificial leather, or'leather substitute.

My method is performed as follows: The fibrous In Germany December 19,

material, whatever it may be, is placed on a screen or other foraminous holder, and another screen or the like is placed on top of the material which may be of any desired thickness between the two holders. The two holders or screens are then moved through a solution or suspension of a binder or adhesive, and, if the method is performed properly, the material is thoroughly impregnated. The impregnated body of fibrous material, together with the two holders o'r screens, is now squeezed by a'pair of squeezing rollers or other suitable machine, and the holders or screens may then be'removed, as the body is now self-supporting. It is placed in a precipitating bath where the binder or adhesive is coagulated so that it loses its stickness and the body obtains the required strength. After the precipitation of its binder or adhesive, the body is again squeezed and finally dried.

By inserting the fibrous material between the two screens or holders and by impregnating it with the binder or adhesive while between the holders, a mostintimate mixture of the fibres and the binder is effected in a simple and efiicient manner. Water-repellent properties may be imparted by adding suitable substances to the binder and/or the precipitating agent.

If latex is used as the binder or adhesive, sulfur and an accelerator may be added to the latex so that vulcanization occurs during the drying of the product. Numerous other binders may be used instead of latex, for instance, viscose, gelatine or taurocolla, starch, celluloid solutions, a rubber-benzin solution of the proper concentration, etc. Fillers may be used and obviously the properties of the fillers must be selected in con- 40 per cent latex kilogrammes Water 40 litres Necal, BX as a damping agent 250 grammes 11 kilogrammes 6 kilogrammes Parafiine-oil emulsion Cumaron-resin emulsion The damping agent Necal, BX is produced on the basis of naphthene acid. Necal, BX is a trade-name for a damping agent produced by I-. G. Farbenindustrie A. G., and is a derivative of naphthalene acid.

The composition of Necals is given in the journal fMelliand Textilberichte Volume XIV, No. 3, Heidelberg, March 1933, page 142.

The time for which the piece or body moves through this mixture, is so determined that the batten will be thoroughly impregnated. The impregnatingvperi'od is comparatively short, frequently under one minute.

The body and the two screens are now taken through a pair of rollers where the excess binder is removed and the fibres are compressed. ,The

screens are then removed and the body'is brought into aprecipitating bath of about 45 grammes of acetate of alumina per litre, and is about degs'. centigrade warm. After the precipitation, the body is again squeezed and then dried, whereupon it may be finished as artificial leather in any suitable manner.

I claim:

A-method of making artificial leather from to about 80 0:, and lastly compressing and drying the cotton mass.

KARL HAARBURGER. 

